Advanced Passive Thermal Management for LED Bulb Systems

2013 ◽  
Vol 2013 (DPC) ◽  
pp. 001277-001293
Author(s):  
James Petroski
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Energy Savings ◽  
Cooling System ◽  
Point Of View ◽  
Hazardous Substances ◽  
Size And Shape ◽  
Lighting Systems ◽  
Liquid Cooling System ◽  
Forced Cooling

The movement to LED lighting systems worldwide is accelerating quickly as energy savings and reduction of hazardous substances (RoHS) increase in importance. Furthering this trend are government regulations, rebate programs and declining prices. The market drive today is to replace light bulbs of common outputs (60W, 75W and 100W) without resorting to Compact Fluorescent (CFL) bulbs containing mercury while maintaining the standard industry bulb size and shape referred to as A19 for fixture retrofitting. This A19 size and shape restriction causes a small heat sink which is only capable of dissipating heat for 60W equivalent LED bulbs with natural convection. 75W and 100W equivalent bulbs require larger sizes, some method of forced cooling, or some unusual liquid cooling system; generally none of these approaches are desirable for light bulbs from a consumer point of view. Thus, there is interest in developing natural convection cooled A19 light bulb designs for LEDs that cool far more effectively than today's current designs. Current A19 size heat sink designs typically have thermal resistances of 5–7 °C/W. A more efficient method of cooling can be created using a chimney-based design to lower system thermal resistances below 4 °C/W while meeting all other requirements for bulb system design. Numerical studies and test data are in good agreement for various orientations including methods for keeping the chimney partially active in horizontal orientations. Such chimney-based designs are capable of cooling 75W and 100W equivalent LED light bulbs in the limited volume constraints of A19-size devices.

Advanced Natural Convection Cooling Designs for LED Bulb Systems

2013 ◽  
Author(s):  
James Petroski
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Energy Savings ◽  
Cooling System ◽  
Point Of View ◽  
Light Bulb ◽  
Size And Shape ◽  
Lighting Systems ◽  
Liquid Cooling System ◽  
Forced Cooling

The movement to LED lighting systems worldwide is accelerating quickly as energy savings and reduction in hazardous materials increase in importance. Government regulations and rapidly lowering prices help to further this trend. Today’s strong drive is to replace light bulbs of common outputs (60W, 75W and 100W) without resorting to Compact Fluorescent (CFL) bulbs containing mercury while maintaining the standard industry bulb size and shape referred to as A19. For many bulb designs, this A19 size and shape restriction forces a small heat sink which is barely capable of dissipating heat for 60W equivalent LED bulbs with natural convection for today’s LED efficacies. 75W and 100W equivalent bulbs require larger sizes, some method of forced cooling, or some unusual liquid cooling system; generally none of these approaches are desirable for light bulbs from a consumer point of view. Thus, there is interest in developing natural convection cooled A19 light bulb designs for LEDs that cool far more effectively than today’s current designs. Current A19 size heat sink designs typically have thermal resistances of 5–7°C/W. This paper presents designs utilizing the effects of chimney cooling, well developed for other fields that reduce heat sink resistances by significant amounts while meeting all other requirements for bulb system design. Numerical studies and test data show performance of 3–4°C/W for various orientations including methods for keeping the chimney partially active in horizontal orientations. Significant parameters are also studied with effects upon performance. The simulations are in good agreement with the experimental data. Such chimney-based designs are shown to enable 75W and 100W equivalent LED light bulb designs critical for faster penetration of LED systems into general lighting applications.

Advanced Natural Convection Cooling Designs for Light-Emitting Diode Bulb Systems

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
James Petroski
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Energy Savings ◽  
Cooling System ◽  
Light Emitting Diode ◽  
Point Of View ◽  
Light Bulb ◽  
Light Emitting ◽  
Size And Shape ◽  
Liquid Cooling System

The movement to light-emitting diode (LED) lighting systems worldwide is accelerating quickly as energy savings and reduction in hazardous materials increase in importance. Government regulations and rapidly lowering prices help to further this trend. Today's strong drive is to replace light bulbs of common outputs (60 W, 75 W, and 100 W) without resorting to compact fluorescent (CFL) bulbs containing mercury while maintaining the standard industry bulb size and shape referred to as A19. For many bulb designs, this A19 size and shape restriction forces a small heat sink which is barely capable of dissipating heat for 60 W equivalent LED bulbs with natural convection for today's LED efficacies. 75 W and 100 W equivalent bulbs require larger sizes, some method of forced cooling, or some unusual liquid cooling system; generally none of these approaches are desirable for light bulbs from a consumer point of view. Thus, there is interest in developing natural convection cooled A19 light bulb designs for LEDs that cool far more effectively than today's current designs. Current A19 size heat sink designs typically have thermal resistances of 5–7 °C/W. This paper presents designs utilizing the effects of chimney cooling, well developed for other fields that reduce heat sink resistances by significant amounts while meeting all other requirements for bulb system design. Numerical studies and test data show performance of 3–4 °C/W for various orientations including methods for keeping the chimney partially active in horizontal orientations. Significant parameters are also studied with effects upon performance. The simulations are in good agreement with the experimental data. Such chimney-based designs are shown to enable 75 W and 100 W equivalent LED light bulb designs critical for faster penetration of LED systems into general lighting applications.

scholarly journals Experimental evaluation of natural convection in the IPR-R1 Triga research reactor at 264 kW and 105 kW

2021 ◽  
Vol 9 (2B) ◽  
Author(s):  
Amir Zacarias Mesquita
Keyword(s):  
Natural Convection ◽  
Technology Development ◽  
Cooling System ◽  
Natural Circulation ◽  
Fuel Temperature ◽  
Operational Parameters ◽  
Reactor Operating ◽  
Core Cooling ◽  
Reactor Pool ◽  
Forced Cooling

In order to study the safety aspects connected with the permanent increase of the maximum steady state power of the IPR-R1 Triga Reactor of the Nuclear Technology Development Center (CDTN), experimental measurements were done with the reactor operating at power levels of 265 kW and 105 kW, with the pool forced cooling system turned off. A number of parameters were measured in real-time such as fuel and water temperatures, radiation levels, reactivity, and influence of cooling system. Information on all aspects of reactor operation was displayed on the Data Acquisition System (DAS) shown the IPR-R1 online performance. The DAS was developed to monitor and record all operational parameters. Information displayed on the monitor was recorded on hard disk in a historical database. This paper summarizes the behavior of some operational parameters, and in particular, the evolution of the temperature in the fuel element centerline positioned in the core hottest location. The natural circulation test was performed to confirm the cooling capability of the natural convection in the IPR-R1 reactor. It was confirmed that the IPR-R1 has capability of long-term core cooling by natural circulation operating at 265 kW. The measured maximum fuel temperature of about 300 oC was lower than the operating limit of 550 oC. It has been proven that without cooling in the primary the gamma dose rate above reactor pool at high power levels was rather high.

Study on the Heat Sink Structure and Heat Transfer Effect of Liquid Cooling System for High Power LEDs

2015 ◽  
Vol 35 (3) ◽  
pp. 0323003
Author(s):  
田立新 Tian Lixin ◽  
文尚胜 Wen Shangsheng ◽  
黄伟明 Huang Weiming ◽  
夏云云 Xia Yunyun ◽  
姚日晖 Yao Rihui
Keyword(s):  
Heat Transfer ◽  
High Power ◽  
Heat Sink ◽  
Cooling System ◽  
Transfer Effect ◽  
Liquid Cooling ◽  
Liquid Cooling System

Design and Optimization of Thermoelectric Cooling System Under Natural Convection Condition

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Xiaoyuan Ying ◽  
Fangming Ye ◽  
Ruitao Liu ◽  
Hua Bao
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Cooling System ◽  
Design Method ◽  
High Reliability ◽  
Experimental Tests ◽  
Heat Sinks ◽  
Thermoelectric Cooling ◽  
Cooling Performance ◽  
Design And Optimization

A design method for the thermoelectric cooling system is improved in this work based on a graphical approach. It is used to select an appropriate thermoelectric cooler (TEC) and determine the value of optimum input current. Theoretical analysis has been conducted to investigate the cooling performance of the system using the design method. Numerical simulation and experimental tests for the entire cooling system validate the calculation result, which indicates the high reliability of the theoretical design method. The temperature dependence of the heat sink resistance and the contact resistance are the major reasons for the small discrepancy. Research is then conducted based on the design method to investigate how a thermoelectric cooling system under natural convection performs, where the optimization of heat sinks at hot side of TEC is done by using the generalized correlations in the previous studies. Comparison is made between the thermoelectric cooling system and the bare-heat-sink system under natural convection. Results show that the thermal resistance of the heat sink attached to TEC is critical to the cooling performance of the whole system. Besides, TEC under natural convection can perform better than the passive cooling if the heat load is not very high (qc″≤20,000 W/m2). The design process and results can provide a useful guidance for other thermal engineers.

Natural Convection Heat Transfer of Annular Metal Porous Medium Heat Sink of LED

2013 ◽  
Vol 284-287 ◽  
pp. 844-848
Author(s):  
Sheng Chung Tzeng ◽  
Tzer Ming Jeng ◽  
Zhi Ting Yeh
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Natural Convection ◽  
Heat Sink ◽  
High Performance ◽  
Cooling System ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Capability

This study used metal porous medium heat sink to replace traditional cooling fins to form a high performance LED cooling system. The metal foamed material has high permeability and cooling area as large as several times of that of traditional fins. With a proper configuration design, it can improve the heat transfer capability of natural convection effectively. This study experimentally investigated the natural convection heat transfer characteristics of the annular metal foamed material, and determined the optimal configuration. The experimental results showed that 1) the heat transfer coefficient (h) increased with ΔT; 2) the (h) decreased as PPI (pores per inch) increased when the thickness (t) of the annular metal foams equaled 5 mm, but the (h) increased as PPI increased when t=11 and 14.5 mm; 3) the (h) increased and then decreased as (t) increased, and there was better heat transfer effect when t=11 mm as shown in the experimental data.

Study on Losses Calculation and Design of DC Boost Chopper

2015 ◽  
Vol 727-728 ◽  
pp. 546-552
Author(s):  
Zhuo Zhang ◽  
Qin Ruo Wang ◽  
Cheng Zhang
Keyword(s):  
Heat Sink ◽  
Power Loss ◽  
Cooling System ◽  
Similarity Theory ◽  
Bipolar Transistors ◽  
Insulated Gate Bipolar Transistors ◽  
Liquid Cooling ◽  
Liquid Cooling System

In view of the cooling of Insulated-gate bipolar transistors (IGBTs) in the parallel DC boost chopper, this paper presents a method to calculate the power loss of IGBTs. It involves functions of equivalent heat circuit of liquid cooling system based on the similarity theory, and the design of the parameters in the cooling system for DC boost chopper. It solves the problems of parameters designing of liquid-cooled heat sink. Taking the cooling system of IGBTs as an example, the experiment shows that the cooling system based on this method has excellent performances in the worksite, and the method is practical and effective.

A Suggestion on Heat Sink Simplification on Natural Convection

2003 ◽  
Author(s):  
Won Nyun Kim ◽  
Choong Ki Kim
Keyword(s):  
Thermal Conductivity ◽  
Natural Convection ◽  
Heat Sink ◽  
Flow Resistance ◽  
Computation Time ◽  
Point Of View ◽  
Working Fluid ◽  
Electronic Systems ◽  
Modified Model ◽  
Thermal Fields

Heat sink is commonly found in electronic systems. For its optimization, numerical computation is introduced. However, narrow gaps between the fins of heat sink have been a troubling factor. That increases the number of grid excessively, and results in increased computation time. The quality of grid can be poor and that halt the accuracy of computed numerical solution. To avoid these problems, many simplification methods are proposed by simplifying complex heat sink. The most popular example is regarding the array of fins as flow resistance from hydraulic point of view and working fluid with different thermal conductivity for thermal equivalence [1]. Its thermal conductivity can be determined according to well-known relationship between Nu, Re, and Pr (see [2, 3]). This simplification presents many advantages but it is not applicable to natural convection. In this paper, a modified model is suggested to extend the simplification to natural convection, which is still popularly applied to electro cooling systems. With the results of [4], thermal conductivity of flow resistance region is iteratively. The modified model is verified by computing flow and thermal fields of PDP. Applying this model to fanless PDP, the number of total grid is reduced by 38.5% percents and corresponding computation time was saved while the accuracy of computed solution is kept undamaged.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

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